Odor flux measurements at a facultative swine lagoon stratified by surface aeration

Abstract

Odor-related complaints are a major concern of pork producers. Open manure storage and treatment facilities such as uncovered anaerobic treatment lagoons are a major contributor to odor nuisance. Repeatable and valid field measurement techniques are needed for evaluating baseline odor emissions from existing livestock facilities and the effectiveness of odor abatement technologies. A buoyant convective flux chamber (BCFC) for measuring odor flux from liquid surfaces of dilute wastewaters was designed, constructed, and tested. Odor flux from a surface-aerated stratified facultative lagoon at a 6000-head swine finishing facility was measured with the BCFC. The swine buildings at this facility contained recirculation flush pits initially charged with about 0.5-m depth of effluent from the second cell of a two-stage lagoon system and discharged weekly to the first cell. The first cell was overloaded by 23% as an anaerobic lagoon with an estimated daily loading rate of about 118 g of volatile solids per m3 of lagoon volume. To mitigate odor nuisance in the surrounding neighborhood, a static-tube aeration system was installed in the first cell in an attempt to create an oxygenated surface layer on an otherwise anaerobic lagoon. Odor flux measurements with the new BCFC appeared to exhibit good repeatability based on a limited number of tests. Odor flux of the stratified lagoon measured using a simulated wind speed of 1.1 m/s in the BCFC averaged 1.72 odor units per s per m2 of lagoon surface area. The results are preliminary in terms of representing annual odor emission rates because odor flux is affected by wind and weather characteristics, results were based on only one constant wind speed that was simulated in the BCFC, and there were relatively few data points. The data was compared with odor flux measured at two unaerated anaerobic lagoons.